python pygame 矩形的翻转

无约束：
x1, y1, x2, y2, x3, y3, x4, y4 = 135, 135, 64, 135, 64, 64, 135, 64

x0,y0 = 100,100

y1 -= 10
y2 -= 10
y3 += 10
y4 += 10

y1 += 10
y2 += 10
y3 -= 10
y4 -= 10

pygame.draw.line(screen, (1, 1, 1), (x0,y0),(x1,y1), 2)
pygame.draw.line(screen, (1, 1, 1), (x0,y0),(x2,y2), 2)
pygame.draw.line(screen, (1, 1, 1), (x0,y0),(x3,y3), 2)
pygame.draw.line(screen, (1, 1, 1), (x0,y0),(x4,y4), 2)

pygame.draw.line(screen, (1, 1, 1), (x1,y1),(x2,y2), 2)
pygame.draw.line(screen, (1, 1, 1), (x2,y2),(x3,y3), 2)
pygame.draw.line(screen, (1, 1, 1), (x3,y3),(x4,y4), 2)
pygame.draw.line(screen, (1, 1, 1), (x4,y4),(x1,y1), 2)

约束：

if y1 < 64 :
    a = False
    print('False')
elif y1 > 135 :
    a = True
if a == False:
    y1 += 10
    y2 += 10
    y3 -= 10
    y4 -= 10
if a == True :
    y1 -= 10
    y2 -= 10
    y3 += 10
    y4 += 10